THE DEPENDENCE OF CROSS-SLIP ON STACKINGFAULT ENERGY IN FACE-CENTRED CUBIC METALS AND ALLOYS,
Abstract
The results of an experimental study of the temperature and strain-rate dependence of tau sub III (the stress at the onset of stage III) for Cu-Zn alloys are described and interpreted in terms of Seeger's theoretical analysis of tau sub III (the stress at the onset of stage III). The values of the stacking-fault energy, gamma, derived in this way are compared with the estimates of gamma for the same alloys obtained directly from electron microscope observations of dislocation nodes. The two sets of values are found to disagree, and the nature of the discrepancy is such as to throw serious doubts on the applicability of the Seeger analysis to Cu-based alloys with e/a>1.10. The lower limits of gamma for pure Cu and Ag, from electron microscope data, are approximately 60 ergs/sq cm and approximately 20 ergs/sq cm; the values of gamma deduced from Seeger's tau sub III analysis are approximately 170 ergs/sq cm and approximately 30 ergs/sq cm respectively. The lower limit of gamma for Cu is inconsistent with the previously accepted figure based on the assumption that gamma is twice the twin boundary energy, and this assumption is now held to be invalid. Seeger's model of cross-slip at Lomer-Cottrell barriers is examined critically, and found to be incompatible with the observations in Cu and Al that screws are held up preferentially. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 05, 1962
- Accession Number
- AD0613726
Entities
People
- P. B. Hirsch
- P. R. Thornton
- T. E. Mitchell
Organizations
- University of Cambridge